iOS - Create a video from array of images and save to camera roll

I am trying to create a flipbook type video out of an array of images using Objective C. I'm currently using AVCaptureDevice to capture a few picture frames per second of output, and am trying to figure out how to convert these images to be a video. I've seen some examples that use AVAssetWriter, but how do I convert to a video that can be then saved to the camera roll?

via Chebli Mohamed